Aphasia is caused by localized brain damage, for example due to a stroke or an automobile accident. General intellectual functioning is not necessarily impaired, as the person can still perform non-linguistic tasks. Nor is the understanding and production of language necessarily completely abolished. Instead, there are highly specific patterns of impairment in the way language is processed.

Is there a critical period? It has been suggested that there is a critical period for children to acquire their first language and that this extends into late childhood and possibly until puberty. Linguistic deprivation The suggestion is, however, difficult to test directly. This…

What is duality in language? What is language productivity? The term duality refers to the organization of language at two levels: primary level units and secondary level elements. This key property enables productivity in language – the ability to construct an infinite set of new and meaningful utterances.

Human language is a complex communication system that allows the generation of infinitely many different messages by combining the basic sounds (phonemes) into words, and combining the words into larger complex utterances. The way the sounds combine is governed by phonological rules, and the way the words combine is governed by syntactic rules. Human language is, therefore, generative and demonstrates duality of patterning. This article explains these concepts.

Children use different semantic functions to express ideas. This is evident in single word utterances known holophrases. A holophrase is a single word – used by infants up to the age of 2;00 years – which has the force of a whole phrase which would typically be made up of several (adult) words. Beyond the so-called One Word Stage, children relate different semantic categories to create meaningful, longer utterances.

An innate ability for language acquisition is the claim that humans are genetically pre-programmed to learn language. Observations such as the uniqueness of the human speech organs, the speed of acquisition of language, the presence of linguistic universals, and the claim that language is unique to humans are all used to support this view.

Language is highly complex but can be defined in terms of a number of key properties. Eight such properties are considered: arbitrariness, duality, systematicity, structure-dependence, productivity, displacement, specialisation, and cultural transmission.